Metal air propeller and the like



H. LEITNER METAL AIR PROPELLER AND THE LIKE Filed Jan. 21, 192? InventorPatented July 15, 1924.

- UNITED STATES PATENT OFFICE.

.HENBY LEITNER, OF LONDON, ENGLAND.

IETAL AIR PROPELLER AND THE LIKE.

Application filed January 21, 1922. Serial No. 580,845.

tageously detachable from the propeller hub and ad ustable therein forvariations of itch and consequentl vary from an aerooil cross section inthe body to a circular cross section at the root.

In carrying out the invention, the blade is made from two sections ofsheet metal folded to form the edges of the blade, the said two sectionsbeing joined by a mechanical longitudinal seam extending along each sideof the blade intermediate of the two folded ed es.

n a suitable arrangement for carrying out the invention, where the bladeis made in two parts, I press or shape each blade so that part of theface and back thereof form one part of the blade lon itudinally with theedge of the blade formed by the bend of the metal between the face andback, including the laminations. This art may be, for example, that ofthe leading edge .of the blade, the other part being that of thetrailing edge. The two portions having the bent edges and which willhave the appearance of long curved troughs are then oined along thecentral or joint line either by lapping the edges of the sheets andriveting, or by a riveted metal strip which may be pressed up from theinside between the longitudinal dividing line, thus adding to thestillness and forming a sort of spar. Or what is known as a tinsmithsjoint may be-used, that is to say, a strip of metal is bent at the edgescompletel round its own thickness and engages wit a similarly bent edgeon the adacent edges of the blades and then both are pressed togetherand the central portion of the stripl is pressed into the dividing linebetween t e said two connected parts of the blades thus also forming aspar and stifiening; the clamped and compressed edges ma be furtherriveted, if desired, or blunt unc marks made therein to further 100 thejoint; the foregoing methods of fixation are mentioned by way of exampleonly as any other known method to secure the two part blades togethermay be employed.

As an alternative construction the blade instead of beinglin two partsmay consist of one part only, is e back or face being shaped so that theedges of the blade are bent and prolonged to form either the back or theace longitudinally, as the case may be, the

two meetin edges being joined together as described a ove.

To enable the invention to be fully under-v stood, I will describe it byreference to the accompanying drawing, in which Fi re 1 is an elevationof a hollow sheet meta propeller blade of the type having a cylindricalstem or root designed to turn in a bearing in the propeller hub forvaryin the pitch, the said b ade being constructed in accordance withthe invention.

Figures 2 and 3 are, respectively, sections on the lines 22, and 33,Figure 1, but drawn to a larger scale.

Figs. 4 and 5 are sections illustratin modifications of the 'oints inthe back an front of the blade illustrated in Figures 2 and 3respectively.

Fi 6 and 7 are similar views to Figures 4 an 5, illustrating furthermodifications.

Fi 8 is a modification of the joint shown in F1 re 7.

Re erring to Figures 1 to 3, a, b are the two parts of the propellerblade and o, d are the respective bends therein constituting the leadingand trailing edges of the blade, each of the said two parts having asomewhat trou hlike form with their meeting edges over apping at aboutthe centre of the blade and being secured by rivets e, or they may besecuredby other means. Figure 2 is a section through the top of theblade where only one lamina is employed, whilst Fi ure 3 is a sectionnearer the root of the b ade where, say, two additional laminae areused, the overla ping joint being arranged as indicated, w ereas, whereall the laminae enter the cylindrical casing f-forming the stem, ther1vets 6 may also pass through the said casing.

Instead of the overlapping joints described with reference to Figures 1to 3 the edges of the parts a and b may butt together as indicated inFigures 4 and 5, the joints being covered by metal strips 9 secured tothe said parts a and b by rivets It Or other means than rivets ma beemployed.

Figures 6, 7 and 8 s 0w different forms of folded or tinsmiths jointsfor uniting the 5 edges of the parts a and b, that illustrated in Figure6 showing the edges of the said arts folded together, the inner laminmin igure 7 being riveted to the said jointed outer lamina b rivets 2'.Figure 8 shows a 10 metal vstri 7' mtermediate of the adjacent edges oft e parts a and b and having the edges connected thereto by folded ortinsmiths joints.

Claim:

A screw propeller of the kind described, formed from two sections ofsheet metal folded to form the edges of the blade, the said two sectionsbeing joined by a longitudinal mechanical seam extending along each sideof the blade.

HENRY LEITNER.

